James Milner suffers injury against Man City
The former England midfielder pulled up holding the back of his thigh after a challemnege with Kyle Walker in the 0-0 draw at Anfield.
He was repalced by Naby Keita, during the top of the table clash.
Gary Neville, commentating for 'Sky Sports' thought this might be linked to Liverpool's recent busy schedule.
He said: "We just had a conversation about the impact of three games in a week, really tough games, with the travelling, and that could be a sign [of fatigue].
"You can pull your hamstring in any fixture at any time, but you are more likely when you are fatigued. You're just not quite right."